Propulsion system for a buoyant vehicle

Abstract

The invention is a propulsion system for a buoyant aircraft. The invention comprises a gas storage container filled with a lighter-than-air gas and having outer walls of which at least a portion thereof are flexible. A system is provided to move the flexible portions of the walls alternately inward and outward varying the internal volume of the container, thus, varying the buoyancy of the aircraft and providing a propulsive force. Air foils mounted on the aircraft are adapted to provide trimming forces as the aircraft descends and ascends.

What is claimed is: 
     
       1. A propulsion system for translating a buoyant aircraft in a generally horizontal direction comprising: buoyancy control means mounted on said aircraft for alternately producing upward and downward thrust forces causing the ascent and descent, respectively, of the aircraft, said buoyancy control means comprising: a gas storage container having walls at least a portion of which are flexible, said container filled with a constant mass of lighter-than-air gas; and   volume varying means coupled to said flexible portions of said wall for alternately causing said flexible portions to move inward from a first position to a second position compressing said gas and decreasing the volume of said container and to move outward allowing said compressed gas to expand and to move from said second position to said first position increasing the internal volume of said container;   force balancing means coupled to said volume varying means for generally balancing the varying force on said flexible portions of said walls as said walls alternately move from said first position to said second position produced by the alternating increasing and decreasing of pressure produced by said gas;   an airfoil mounted to the aircraft for providing a lift force generally opposing the upward and downward thrust as the aircraft ascends and descends; and   trimming control means for providing pitch control as the aircraft ascends and descends such that a portion of the lift force is directed along the desired flight path.     
     
     
       2. A propulsion system for translating a buoyant aircraft in a generally horizontal direction comprising: buoyancy control means mounted on said aircraft for alternately producing upward and downward thrust forces causing the ascent and descent, respectively, of the aircraft, said buoyancy control means comprising: a gas storage container having walls at least a portion of which are flexible, said container filled with a constant mass of lighter-than-air gas; and   volume varying means coupled to said flexible portions of said wall for alternately causing said flexible portions to move inward from a first position to a second position compressing said gas and decreasing the volume of said container and to move outward allowing said compressed gas to expand and to move from said second position to said first position increasing the internal volume of said container, said volume varying means comprising: cable means having first and second ends, said first ends of said cable means coupled to said flexible portion of said walls of said container;   spool means coupled to said second end of said cable means for receiving said cable means; and   drive means coupled to said spool means for alternately winding and unwinding said cable means on said spool means; and   torque balancing means coupled to said spool means for generally balancing the torque applied to said spool means by said cable means as said flexible portions alternately move from said first position to said second position;     an airfoil mounted to the aircraft for providing a lift force generally opposing the upward and downward thrust as the aircraft ascends and descends; and   trimming control means for providing pitch control as the aircraft ascends and descends such that a portion of the lift force is directed along the desired flight path.     
     
     
       3. The propulsion as set forth in claim 2, wherein said torque balancing means comprises; a torsional spring coupled to said spool means; and   said spool means having a variable diameter along its length such that said spring applies a torque to said spool means substantially equal to the torque produced by said flexible portions as said flexible portions move alternately from said first position to said second position.